#搜一下简化符号 += ，然后用 += 重新写这个脚本。
"""a = a +1
a +=1"""
from sys import argv

script, input_file = argv


def print_all(f):
    print(f.read())

def rewind(f):
      f.seek(0)

def print_a_line(line_count, f):
    print(line_count, f.readline())

current_file = open(input_file)

print("First let's print the whole file:\n")

print_all(current_file)

print("Now let's rewind, kind of like a tape.")

rewind(current_file)

print("Let's print three lines:")

current_line = 1
print_a_line(current_line, current_file)
current_line += 1
print_a_line(current_line, current_file)
current_line += 1
print_a_line(current_line, current_file)
